1. Field of the Invention
The invention relates to a semiconductor memory device such as a NAND flash memory, and more particularly, relates to a scrambling method for data in the NAND flash memory.
2. Description of Related Art
The NAND flash memory has a memory array including a plurality of blocks. A NAND string is formed by connecting a plurality of memory cells in series in one block. Typically, data is read or programmed in page units, but erased in block units.
Patent Document 1 discloses a data writing method for improving an operating reliability of the NAND flash memory. Said writing method selects a scrambling method based on an address of a word line, scrambles data to be written according to the selected scrambling method, and writes the scrambled data to a corresponding page.